Prognostic value of transvalvular flow rate in patients with low-gradient severe aortic stenosis: A dobutamine stress echocardiography study.

Abstract

There are limited data on the clinical relevance of transvalvular flow rate (Qmean ) at rest (Qrest) and at peak stress (Qstress ) during dobutamine stress echocardiography (DSE) in patients with low-gradient severe aortic stenosis (LG-SAS). We retrospectively analyzed the clinical data of patients with LG-SAS who underwent DSE. LG-SAS was defined as an aortic valve (AV) area index of<.6 cm2 /m2 and a mean AV pressure gradient (AVPG) of<40mm Hg. The primary endpoint included all-cause death and heart failure hospitalization. Of 100 patients (mean age 79.5±7.3 years; men, 45.0%; resting left ventricular ejection fraction [LVEF] 52.1%±15.9%; resting stroke volume index 35.8±7.7mL/m2 ; Qrest 171.8±34.9mL/s), the primary endpoint occurred in 51 patients during a median follow-up of 2.84 (interquartile range 1.01-5.21) years. When the study patients were divided into three subgroups based on Qrest and Qstress , the multivariate analysis showed that Qrest<200mL/s and Qstress ≥200mL/s (hazard ratio 3.844; 95% confidence interval 1.143-12.930; p=.030), as well as Qrest and Qstress<200mL/s (hazard ratio 9.444; 95% confidence interval 2.420-36.850; p=.001), were significantly associated with unfavorable outcomes with Qrest and Qstress ≥200mL/s as a reference after adjusting for resting LVEF, resting mean AVPG, chronic kidney disease, New York Heart Association functional class III/IV, and AV replacement. Flow conditions based on the combination of Qrest and Qstress are helpful for risk stratification in LG-SAS patients.